#include <limits>
#include <iostream>
using namespace std;
int x;
void tesr1()
{
	enum flag {x=1,y=2,z=4,e=8};
	cout<<numeric_limits<float>::max()<<endl;
	cout<<numeric_limits<char>::is_signed<<endl;
	cout<<"int size"<<sizeof(int)<<endl;
	cout<<"float size "<<sizeof(float)<<endl;
	cout<<"long size  "<<sizeof(long)<<endl;
	cout<<"double size "<<sizeof(double)<<endl;
}
void test2()//the use of const point
{
	int i=9;
	int j=0;
	int *const pi = &i;
	*pi=10;
	cout<<*pi<<endl;
	cout<<i<<endl;
	//pi =&j;
	//cout<<*pi<<endl;
}
void test3()
{
	int x=2;
	{
		int x=3;
		//::x=4;//the x is a global variable
		cout<<x<<endl;
	}
	cout<<x<<endl;
	cout<<::x<<endl;
	double d;
	cout<<d<<endl;
}
int main()
{
	test3();


}